Minimal Residual Disease [MRD]

Tiny cells, Big Impact: MRD- A silent hero in cancer care:

What is minimal residual disease?

Cancer is a dreadful disease that often involves a multidisciplinary treatment approach through a wide array of diagnostic techniques to completely eradicate the tumor cells. Minimal residual disease refers to the small amount of cancerous cells that tend to remain in the body even after you have undergone a successful cancer treatment. These cells pose a threat to relapse in patients.

Let us say you have undergone a successful cancer treatment involving chemotherapy, but the ultimate result lies in the eradication of tumor cells; there is a scenario in which some of the tumor cells may lie beneath the shadows, remaining undetected by conventional diagnostic techniques. This occurrence is crucial to determining the success of therapy and identifying the relapse of cancer. It is often used as a predictor for cancer relapse. Join us as we unveil the stories behind MRD and its significance in cancer care.

Minimal residual disease - Tests to identify

MRD testing can identify even the small number of cancerous cells in the body; it is accurate that it can even differentiate 1 cancerous cell even among 1 million healthy cells. In many cases, the number of tumor cells is very small enough to cause a carcinogenic effect or symptoms, but it can pave the way for future relapse.

The sampling procedure for the diagnosis involves bone marrow aspiration, where the patient is given a sedative and a bone marrow fluid sample is collected from the hip or chest bone. The various testing methods available for detecting MRD include, 

1. Polymerase chain reaction [ PCR] - This test expands the DNA fragments within the bone marrow and blood cells, making detecting the cancerous cells easy. It can even detect the tumor among a million normal cells. The test result usually takes 5-14 days to show up.
2. Multiparametric flow cytometry- This method employs antibodies to detect the presence of protein markers necessary for the identification of cancer cells. Test results are generally available in less than a day.
3. Next-generation sequencing [NCS]- This method identifies abnormal genetic characteristics by using sequence detection of DNA and RNA. Test results can be obtained after 10-14 days.
4. Fluorescence in situ hybridization - This technique identifies specific DNA sequences on chromosomes and helps to identify genetic abnormalities and comparisons.
5. Immunohistochemistry- This technique uses the antibody-antigen binding principle to identify cellular abnormalities.

These tests are often employed in various blood cancers such as leukemia, lymphoma, and myeloma, where conventional relapse indicative tests may not be accurate, and sometimes other kinds of cancer such as lung cancer, colorectal cancer, and breast cancer. The combinational use of multiple testing techniques can increase the chances of identifying the MRD cells.

When a patient has tested positive for MRD by these testing methods, it indicates that there are still some residual cancerous cells in the body even after treatment. Still, a positive result does not guarantee a complete relapse, but there is a risk of cancer being developed. Negative test results are an indication that there were no cancerous cells found in the body. Patients with negative MRD tests have longer reemissions and an extended rate of survival.

Criteria for testing

It is ideal to test for MRD cells after the final cycle of treatments like chemotherapy or combinational therapy. It can also be tested during the treatment procedure to find out the remission of cancer. It is also employed for testing during or after bone marrow transplants. However, accurate test results depend on identifying specific tests needed and sometimes also a combinational approach to tests.

MRD testing and its aid in treatment strategies

Testing for MRD becomes crucial in identifying cancer patients who need the extra care and to determine the need for further treatment plans. The knowledge of MRD cells and diagnostic methods aims not only to eradicate the remaining cancer cells but also to prevent any resistance that develops as the treatment progresses. 

Let us see how MRD testing can aid in cancer treatments:

1. It helps to confirm the remission of cancer and helps in further monitoring.
2. Identifying the recurrence of cancer at a faster rate than other diagnostic tests
3. It identifies the patients needed to restart the treatment.
4. It helps healthcare professionals to find the best treatment options like combinational therapy and stem cell transplantations.
5. It reveals how well the cancerous cells have responded to the treatment.

The treatment options can include, 

1. Stem cell transplant- It involves the replacement of bone marrow that is damaged by transplanting blood stem cells, further traveling to the bone marrow to produce new blood cells.
2. Targeted therapy- It involves various drug molecules that target the specific tumor cells alone, unlike conventional cancer chemotherapy harming even the healthy cells. Various drugs include protease inhibitors, monoclonal antibodies, Immunomodulating drugs, etc.

     3. Combinational therapy includes radiation therapy and chemotherapy.

Myths and Facts

Myth: If I'm in remission, there is no need to worry about Minimal residual disease

Fact: Remission does not guarantee a complete eradication of cancer cells; MRD detection is crucial, even in this case, to eliminate the risks.

Myth: MRD testing is employed only for certain types of cancer

Fact: It is, however, being used for certain types of blood cancer like leukemia, lymphoma, and myeloma; it is also being addressed for lung, breast, and colorectal cancers.

Myth: If MRD is detected, then the treatment has failed.

Fact: It does not indicate the failure of treatment. However, it helps clinicians analyze the depth of treatment effects in the body for better outcomes.

Conclusion

Minimal residual disease has fallen under the radar of the spotlight as a vital factor in cancer treatment approaches. It significantly boosts the hopes of patients, thereby offering a personalized and promising treatment for cancer relapse. As research and studies progress, understanding MRD will play a vital role in establishing a future where cancer is not only treated but can be conquered.

 "From Darkness to Light: Together, We End Cancer's Fight."